With the ZED mixer disconnected from the Apple Mac, start a new GarageBand session, delete any audio tracks to create a blank template (highlight track then click ‘Track’ and select ‘Delete Track’).
Plugin the USB cable from the ZED into an available USB port on the Mac, a prompt window will appear on the screen informing the USB Audio CODEC has been recognised and it will ask if you would like to use this device, select YES, this will configure the ZED soundcard as the input and output audio device for GarageBand.
This can be checked in the GarageBand ‘Preferences’ page under the 'Audio/MIDI' tab and should look like this:
Audio Output: USB Audio CODEC
Audio Input: USB Audio CODEC
Close the ‘Preferences’ page then create a new ‘Real Instrument’ using the ‘Add Track ‘ option.
The ‘Input Source’ setting in the ‘Track Info’ window on the right side of the screen should display:
Stereo 1/2 (USB Audio CODEC)
Set the desired routing and recording levels on the ZED mixer then arm/enable the track to record, once the track is armed the level meters should display the signal from the mixer. If the signal level is low the gain structure may need to be adjusted from the mixer.
With the levels set, hit 'Record' on the 'Transport bar' to commence recording.
Once the recording is complete, hit ‘Play’ on the 'Transport bar' to playback the recorded audio on the ZED mixer USB return/playback channel.